This relates generally to electronic devices with displays, and, more particularly, to displays with backlights.
Electronic devices such as computers and cellular telephones have displays. Some displays such as plasma displays and organic light-emitting diode displays have arrays of pixels that generate light. In displays of this type, backlighting is not necessary because the pixels themselves produce light. Other displays contain passive pixels that can alter the amount of light that is transmitted through the display to display information for a user. Passive pixels do not produce light themselves, so it is often desirable to provide backlight for a display with passive pixels.
In a typical backlight assembly for a display, a light guide layer is used to distribute backlight generated by a light source such as a light-emitting diode light source. Optical films such as a diffuser layer and prism films may be placed on top of the light guide layer. A reflector may be formed under the light guide layer to improve backlight efficiency.
A strip of light-emitting diodes may provide light to an edge of a light guide layer. Light from the strip of light-emitting diodes is initially concentrated in the vicinity of the outputs of the light-emitting diodes. The light must travel a sufficient distance into the light guide layer to mix enough to be used as backlight illumination. Backlight units that require large mixing distances may consume more volume within a display than desired.
It would therefore be desirable to be able to provide displays with improved backlights.